Summary:
Hesler(2) (describing the holotype collection from CA) gives the distinctive features as a reddish brown cap with minute yellow fibrils, a heavy ventricose stem, subsinuate gills, slightly dextrinoid spores and interwoven cap tissue. Other features include the large size of the cap (up to 40cm across), yellow unchanging flesh, pale brown young gills, a pale brownish stem with white fibrils in the upper part and often yellow fibrils further down, a persistent ring with a jagged margin, bitter taste, and fruiting in groups and tufts on conifer trees and stumps. |This is the best established member of the Gymnopilus ventricosus group for the Pacific Northwest, although Gymnopilus voitkii is also confirmed by molecular study. |The Hesler(2) and Thorn(7) field descriptions are both based on the original field notes with the type collection by C.F. Baker, and therefore lack the full range of characters such as larger cap size, brownish orange to orange yellow colors in the cap, and rusty brown spore print. |Arora refers to this as the large non-hallucinogenic conifer-loving western member of the Gymnopilus spectabilis group [here called the Gymnopilus ventricosus group] with a swollen stem and membranous veil, that can reach more than 40cm in diameter, noting that young specimens "present an entirely different appearance: squat and compact with hard, very thick, yellow flesh and very narrow (shallow gills)". |Trudell(4) comment in 2009 about the Pacific Northwest, with Latin names italicized, "Two such species occur in our region. The more common one is Gymnopilus ventricosus ... The less common species in our region, G. junonius (=G. spectabilis), occurs on both conifer and hardwood substrates and typically is somewhat smaller with a thinner stipe." This was before the description of G. voitkii, and the current status of Gymnopilus junonius (and Gymnopilus spectabilis) in the Pacific Northwest is uncertain. |Many collections identified as G. spectabilis are in fact G. ventricosus (Stamets).

Cap:
7-8cm across, convex, obtuse; reddish brown, often with a lighter disc; subdry [more or less dry], minutely yellow-fibrillose or almost bald, margin subappendiculate from hanging fibrous veil remnants, (Hesler), up to 40cm or more across, (Arora)

Flesh:
pale yellow, unchanging, (Hesler)

Gills:
subsinuate, crowded, rather broad and subventricose [somewhat broader in middle]; pale brown becoming dark cinnamon; edges thin and entire, (Hesler), "subsinuate, broad and subventricose", crowded; "light brown, dark cinnamon in age", not marginate, (Thorn)

Stem:
14-18cm x 2-3cm, solid, conspicuously ventricose [wider in middle]; pale brownish; with white fibrils in upper part and with fine yellow fibrils (or more or less bald) lower down, rooting and covered with a white mycelium at the base, (Hesler), 14.0-18.0cm x 2.0-3.0cm, "strongly ventricose, largest below the middle, sometimes subradicating"; "pale brown, yellow fibrillose to subglabrous, white-mycelioid below, densely white-tomentose at the apex, annulate", (Thorn), swollen stem with membranous veil (Arora)

Veil:
forms a thick persistent almost apical ring with margin jagged and remaining erect, (Hesler), partial veil "forming a flaring and persistent annulus", almost apical on the stem, (Thorn)

Odor:
none (Hesler), non-descript mushroom odor (Thorn)

Taste:
bitter (Hesler, Thorn)

Microscopic spores:
spores 7.5-9 x 4-5.5 microns, elliptic, oval or subamygdaliform [somewhat almond-shaped] in face view, inequilateral in side view, verruculose [finely warty], no germ pore, slowly dextrinoid; basidia 4-spored, 23-27 x 6-8 microns; pleurocystidia 27-31 x 6-7 microns, "fusoid-ventricose or flask-shaped, often with a brown pigment", cheilocystidia 26-33 x 5-8 microns, "flask-shaped with a neck, more or less capitate"; gill trama subparallel to parallel, hyphae 5-7 microns wide; cap trama interwoven, cuticle "of more or less repent hyphae bearing tufts of pallid to brownish hyphae"; clamp connections present, (Hesler), spores (6.6)6.7-9.1(10.2) x (4.0)4.3-5.2(6.3) microns, average = 7.9 +/- 0.6 microns x 5.2 +/- 0.5 microns, amygdaliform, with conic apices, "finely to coarsely roughened with irregular warts and ridges, darkening in 5% KOH, strongly dextrinoid; basidia 4-spored, 24.0-39.3 x 6.4-8.6 microns, clavate to cylindric, "usually constricted near or above the middle, occasionally stipitate"; cheilocystidia "mostly lageniform but with apex often slightly to moderately swollen and thus lecythiform, length 22.4-42.5(46.8) microns, in widest part (3.2)4.4-8.9(10.8) microns, at neck (1.4)1.7-3.7(3.8) microns wide, at head (2.2)2.5-5.7(5.8) microns wide, pleurocystidia scattered, similar to cystidia, length 24.9-43.3(45.9) microns, width at widest point 5.9-9.8 microns, at neck 0.8-5.2(5.5) microns wide, at head 2.6-6.7(7.0) microns wide; caulocystidia "abundant above the annular zone, produced as terminal cells of long hair-like hyphae, narrowly ventricose-capitate to cylindric-capitate, sometimes cylindrical and without significant apical swelling", length 41.0-73.3 microns, width at widest point 2.0-7.7(11.2) microns, at neck 1.4-4.8(5.1) microns wide, at head 2.5-7.3 microns wide; clamp connections "present on nearly all septa", (Thorn)

Spore deposit:
rusty brown (Phillips)

Notes:
The holotype is from CA. Thorn(7) examined and sequenced collections from BC as well as the CA holotype. Collections from BC labeled as G. ventricosus were deposited at the University of British Columbia: 3 are G. ventricosus and 1 is G. voitkii based on sequencing by Thorn(7). G. ventricosus has been recorded (before the description of G. voitkii which must be differentiated microscopically or by molecular study) from Cape Lookout on the OR Coast, in Olympia, WA and in northern ID (by M. Beug, pers. comm.).

EDIBILITY

no (Phillips), not hallucinogenic (Stamets)